Comparative analysis of excretion of six major compounds of Polygonum orientale L. extract in urine, feces and bile under physiological and myocardial ischemia conditions in rats using UPLC-MS/MS

Polygonum orientale L. is a traditional Chinese medicine having extensive pharmacological activities including antimyocardial ischemia (MI) injury properties. Isoorientin, orientin, vitexin, quercitrin, astragalin and protocatechuic acid are the main compounds in P. orientale extract. The aim of this study was to establish an ultra-performance liquid chromatography-tandem mass spectrometry method for the determination of the content of these compounds in urine, feces and bile samples simultaneously and application of the method in a comparative excretion study in normal and MI model rats after oral administration of P. orientale extract. Chromatographic seperation was conducted on an Agilent Eclipse Plus C₁₈ column with the mobile phase consisting of 0.1% formic acid-acetonitrile and 0.1% formic acid-water. Negative ion multiple reaction monitoring mode was used for quantification. The six compounds had good linearity (r ≥ 0.9921) and acceptable accuracy ranging from 10.10 to -5.82% The relative standard deviations of within-day precision and inter-day precision were <10.45 and 13.44%, respectively. The extraction recovery of the six analytes ranged from 80.31 to 101.47% and the matrix effect was 82.56-102.88%, indicating that the preparations of sample collected form urine, feces and bile were stable throughout analysis. The excretion amount of the six analytes increased in both normal and MI model rats' urine, feces and bile in a 24 h period and became stable between 36 and 48 h after administration. The total excretion rate of six compounds was <5% in urine, feces and bile of normal and MI model rats. The excretion peak period for all compounds in MI rats was slower than that in normal rats. This excretion study provides insights for further application and research on P. orientale.